A pollutant that is not broken down by natural processes. Some nondegradable pollutants, like the heavy metals, create problems because they are toxic and persistent in the environment. Others, like synthetic plastics, are a problem because of their sheer volume. One way of dealing with nondegradable pollutants is to reduce the quantity released into the environment either by recycling them for reuse before they are disposed of, or by curtailing their production. A second method is to find ways of making them degradable. Scientists have been able to develop new types of bacteria, for example, that do not exist in nature, but that will degrade plastics.